On Thu, 2018-05-10 at 01:38 +0000, Ryan Taylor wrote: > > If this is correct, using the servercert option is a significant security > problem. > > Perhaps the servercert option is not intended to be used for any sort of > security guarantee > whatsoever. However if that is the case, there should probably be a warning > in the man page, and > also printed on standard output, kind of like overriding a web browser to > connect to a site with an > untrusted certificate. Users who have not done the math or read the man page > carefully may be using > this option with the mistaken belief that it provides some security assurance > via a sort of > makeshift certificate pinning. > > Or, this could be fixed by requiring a complete match of the hash instead of > just 4 characters. > What are the "certain testing use-cases" and how important are they compared > to the security > considerations?
Hi Ryan, thanks for looking at this. As Dan says, if a user provides a truncated hash then we do require the match to be at the beginning of the hash. It's not just *any* substring. Even so, yes: 4 characters isn't many, so there's a fair chance of a false match. Ultimately, Don't Do That Then. I'm happy to improve the documentation to make it clear that there is absolutely no excuse for a user to use anything less than the full hash in "production" use, or indeed in any circumstance where cut-and-paste works. I vaguely recall that I had similar reservations when this feature was first added (Nikos, was it you?). But I *have* found it useful occasionally in testing, in strange setups where I haven't been able to cut and paste for some reason. At the time, we were forcibly removing the "--no-cert-check" option because I threw my toys out of the pram after finding people advocating its use in production — so even a 4- char match was better than that! :)
smime.p7s
Description: S/MIME cryptographic signature
_______________________________________________ openconnect-devel mailing list openconnect-devel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/openconnect-devel
